The field of the invention is drawer suspension systems. More particularly, the field of the invention relates to precision drawer slides for mounting drawers in a carcass.
Drawer suspension systems are used in numerous applications ranging from residential furniture, office furniture, institutional furniture, and in other applications such as toolboxes, cash registers, and photo copying machines, to name a few.
The basic configuration of a drawer suspension system relies on a first part, which may comprise a metal channel member, that is mountable to the side wall of a carcass, and a second part which may comprise a metal channel member that is mountable to a drawer, with means provided in-between the first part and the second part for allowing travel such that the drawer may be moved from a closed position to an open position and vice-versa. There are distinctions that are made between the types of products that serve to function as part of a drawer suspension system, with two member roller slides occupying the lighter duty requirements such as kitchen cabinets, while mid-range and higher duty requirements are handled by three membered slides and the group as a whole is known as xe2x80x9cprecisionxe2x80x9d drawer slides. Many of these are typified by the usage of ball bearing assemblies for translational movement.
Many examples of precision drawer slides are known in the art, including U.S. Pat. No. 6,033,047, (Hoffman), U.S. Pat. No. 5,466,060, (Hoffman) and U.S. Pat. No. 4,469,384, (Fler). Typically, precision drawer slides are characterized by the usage of ball bearings to provide the inter connection between the channel members and to provide for translational movement between the members. Precision drawer slides include particular design approaches such as those where the members telescope, one inside the other, or where the members may be positioned one over the other vertically and are linked by an interconnecting plate, or where various members may be xe2x80x9cgangedxe2x80x9d in a back-to-back treatment. The design characteristic that is selected is dependent in part on the particular application to which the slide is being directed, or the type of loading that will be anticipated to be encountered once in use.
In addition to the foregoing, there are other considerations in precision drawer slide technology. The selection between the types of drawer slide movement may be preferentially drawn towards a sequential acting drawer slide or a progressive acting drawer slide. In the former, the members of a telescoping type precision slide, for instance, can be made to open in a very selective manner, such that the cabinet member, which typically remains fixed, supports an intermediate member (or center member) and a drawer member both of which substantially xe2x80x9cnestxe2x80x9d into the envelope of the cabinet member profile. The drawer member is attached to the drawer, carrying the drawer and its contents. When a precision drawer slide of this type is opened in a sequentially acting version, the intermediate member and the drawer member move forward in unison, owing to the particular sequential engagement device involved, until the center member reaches the end of its forward travel. At that point, the drawer member is then released from the sequential engagement device and is allowed to continue the forward travel until it reaches its end. In this fashion, the loading efficiency is maximized as between the points on the drawer member and the intermediate member during the early stages in the opening of the drawer. In the forward most position, it can be appreciated that the load is substantially cantilevered over the outward most points of the drawer slide travel reducing the spreading of the load since it is asserted over a smaller contact zone as between the drawer member contact with the intermediate member, and similarly, with the intermediate member contact with the cabinet member. The actual transmission of the loading occurs normally through the ball bearings until the load is received by the cabinet member. In the sequential action described, it is believed that the ball bearings in the cabinet races actually operate under conditions of less pressure as the slide is opened since the loads are not cantilevered as they would be in other slide designs. When sequential action is used, the load is distributed across more portions of the drawer member and the intermediate member in the early stages of the opening procedure which is beneficial to the performance and durability of the drawer slide.
In the alternative, a progression type movement is known whereby, using the same example cited above, the intermediate member and the drawer member are made to move simultaneously in the forward direction. The advantage of this progressive movement is that the load capacities are still being dispersed efficiently, to a large extent (although not as completely as they are in the sequential acting drawer slide). Even though the forward end of travel for both the intermediate member and the drawer member are reached at pretty much at the same point in time, the actual speed at which each member travels is not the same. Typically the drawer member has to travel its full length before it reaches the fully opened position while the intermediate member travels approximately about half its length. This results in the drawer member being progressively moved at about twice the speed at which the intermediate member travels.
One clear advantage of the progression type of movement is the fact that it is actuated by frictional engagement with a rolling surface in the usual mode. This circumvents the traditional noise that is incurred in the sequential acting drawer slides which is caused by the sequential engagement mechanism (typical a latching device) as the intermediate member and drawer member engage and release and engage and release during the operation of drawer opening and closing. It should be apparent and realized that in both circumstances, the sequential acting drawer slides and the progression action type drawer slides that the reverse phenomena happens with respect to the functioning of each type movement during the closing process.
Lastly, random action is probably the most prevalent means by which telescoping precision slides operate. In this mode, there is no functional assistance to dictate the sequence or progression of member actuation. It basically occurs as a consequence of the forces applied to the drawer when opened, which are transmitted in a serendipitous manner to the slide elements. In most cases, the drawer member is opened first, with the center member proceeding thereafter as a matter of being urged open by contact with the drawer member and/or ball bearing retainer. The actual modality for the opening procedure in a random action slide will vary as the particular slide design, the age of the slide, the load being carried, and as the name implies.
In both the random action and sequential action type of telescoping slides it is known that the contact between the members, and/or the ball bearing retainer, will result in undesirable noise and the transmission of the contact impact as for example, the center member is picked up by the drawer member during opening, or when the center member impacts the cabinet member which may occur prior to the time when the drawer member reaches it full extension.
Turning now to other aspects of precision drawer slide technology, there has been a long standing design approach with respect to the configuration of the channel members that make up the precision drawer slide product itself. The channel members, as the name implies, are roughly xe2x80x9cC-Shapedxe2x80x9d and the height and width of the various components of the web and flanges making up the member may vary with the application, the load that is anticipated, and the design envelope that may be available to the manufacturer. With respect to precision drawer slide members; it is believed that the prior art relies on only two basic types of members to achieve the desired functions. The first type is where the flanges that emanate from the channel web are formed as flat areas, such that the point at which the flanges and the web meet, they are roughly perpendicular to each other. (As may be appreciated, the end of the flange typically terminates in a lip, or second flange, which is used to retain the ball bearing once the channel members are assembled).
In another approach, the flange portions of the channel members are radiussed and the chord that intersects the terminal points of the radius, is again, roughly perpendicular to the web of the channel member.
What is important regarding these channel designs is that the flange portions serve to provide the surface for the ball bearings to travel upon, which in the art are termed raceways or races. In the case of the former, or flat flange portions, the raceway may be pre-formed into the surface of the flange providing a very modest radius for the ball bearings to roll upon, as in U.S. Pat. No. 6,033,047, or they may be worn in or xe2x80x9cworkedxe2x80x9d during actual usage and under load. In the case of the radiussed type of profiles, the raceways are initially formed as a consequence of the formation of the flange. Thus, it can be realized that the flange portions of the channel members are responsible not only for providing the surfaces for the ball bearings to contact and rotate during the actuation of drawer opening or closing, but in addition, and perhaps most importantly, the flange portions cooperate in resisting the lateral and torsional forces that are impressed upon the drawer slide during operation as well. It is this function of the channel members, and in particular the cabinet member, that quite often fails pre-maturely in the various prior art drawer slide designs.
It has also been a long standing desire and objective in the art to be able to use thinner gauge metals for the fabrication of the drawer slide channels which would provide a more economical drawer slide construction. The prior art channel designs possess the limitations on their performance as described above though, and attempts to reduce metal thickness therefore are inappropriate when the application of lateral and torsional forces results in failure of the drawer slide. This problem, it is believed, comes from the fact that the geometric configuration of the standard channel profile is not the most rigorous form for resisting lateral and torsional forces. In actual use, the flange ends are susceptible to deformation under the loads that can be applied to a drawer slide and the most critical flange performance is that of the cabinet member and, more specifically, the lower flange element.
In many of the failure modes that the applicant has observed, the lower flange has deformed so catastrophically at the point of failure that the whole drawer slide assembly becomes disengaged at times. Upon examination, other elements of the drawer slide assembly have retained their essential characteristics to a large extent, thus, if a solution could be found for reducing the tendency for flange deformation, it would increase the performance characteristics of the precision drawer slide product substantially.
The deformation of the flange is believed to come about by at least two different factors. The first relates to the effects of the contact made by the ball bearing under load onto the surface on the raceway of the cabinet member. Again, of particular interest is the lower raceway which handles a good deal of the load as the drawer is opened and closed. Most of this concern is focused at the front of the cabinet member where the load is maximized when the drawer is fully opened. As the ball xe2x80x9cworksxe2x80x9d the metal in the trough of the raceway observable changes occur in the configuration of the profile. These changes are inelastic deformations that are caused by the impression of load onto the small contact zone where the ball meets the surface of the raceway. This will actually result in the deformation of the metal at the contact zone causing it to be pushed or mounded until equilibrium is established between the size of the load and the ability of the contact zone to distribute the load.
It has been observed that when the metal is worked in this fashion, there is a corresponding reaction on the part of the flange end extending outwardly (away from the sidewall of the cabinet) such that it tends to xe2x80x9cunwrapxe2x80x9d from its original xe2x80x9cCxe2x80x9d shaped profile. This movement may result from a couple of different factors including the changing of stresses in the steel itself as the ball works the surface of the raceway. Notwithstanding, the effect is detrimental and is at least one factor in the unwrapping of the xe2x80x9cCxe2x80x9d shaped profile, which ultimately leads to the failure of the slide if left unchecked.
A second method of deformation occurs with respect to that portion of the flange end that extends from the raceway back to the flat web portion of the channel member. This portion of the flange is a transitional element between the flat web and the full radius portion of the xe2x80x9cCxe2x80x9d profile. In one sense it can be considered a xe2x80x9cbeamxe2x80x9d with respect to the physics of the situation. For instance, as the drawer slide is moved to an open position, the ball bearings traverse the channel in the raceways and typically, under some loading. The flange ends of the xe2x80x9cCxe2x80x9d shaped profile act somewhat like springs in that they react to the loading by elastically deforming in the direction of the load. In the present case, the bending occurs at that portion of the flange that extends from the race back to the web zone of the channel member.
The spring action as may now be appreciated, is detrimental in more than one way. The elastic deformation that occurs is uncontrolled insofar as the tolerances considered in the drawer slide design, even at the time the slide is first opened. Thus when it occurs, and the degree to which it occurs affects the functioning of the other components of the drawer slide. Aside from the xe2x80x9cfit and feelxe2x80x9d issues that arise from this, the slide components are affected functionally to the extent they may shift in ways that can cause further deformations.
As time goes on, the continued cycling of the drawer slide using a xe2x80x9cCxe2x80x9d shaped profile will obviously cause the spring action to cycle as well. Obviously conditions of load, the materials invested in the drawer slide construction, and the application in which it is installed will all affect the degree to which the spring action impacts the cabinet member profile, but it is known that these conditions do combine at times to cause irreversible deformations or fractures in the flange portion described presumably as the result of metal fatigue. This deformation then adds to the problem previously described with respect to the unwrapping of the flange as the ball works the raceway surface.
Additionally, one of the dynamic requirements that have long been associated with the standard precision drawer slide construction lies in the fact that the loads on the slides are cantilevered. Historically, these precision drawer slide designs have attempted to maximize the amount of cantilever that can be obtained using the conventional channel member approach, however, these approaches still have not met the full utilization of the cantilevered potential of the telescoping members.
It has been, therefore, one long-standing desire and objective in the industry to develop a precision drawer slide design that, to the extent possible, increases or maximizes the cantilevered effect. The reason for this objective results from the ability to reduce the length of the telescoping members the more one can achieve a cantilevered effect. Reducing the length of the members, therefore, reduces the amount of material commitment and ultimately the cost of the precision drawer slide product. The amount of cantilevered positioning in telescoping precision drawer slides has been inhibited by limitations on the amounts of loading that can be sustained in practice, whether this be static loads, lateral or torsional loads, owing at least in part, to the traditional xe2x80x9cCxe2x80x9d shaped design channel construction. With a more robust cabinet member, the amount of the cantilevered positioning that can be obtained will increase correspondingly.
There is the mirror image consideration as well. The limitations of the xe2x80x9cCxe2x80x9d shaped profile has resulted in the specific selection of metal thickness for the makeup of slide members that correspond to the loadings and applications that the drawer slides would be directed towards. It has been a longstanding objective in the industry to be able to reduce metal thickness while maintaining the requisite load and performance characteristics. Thus for a particular design approach, there will be a compromise reached between the amount of cantilevering that is achieved as against the amount of metal thickness that is invested in the channel members. Where it is possible to either increase the cantilevering effects, or to reduce the metal thickness, while maintaining traditional loadings and performance, then an improvement in the economy of manufacturing the product has been realized.
The prior art also discloses the usage of what as known as a quick disconnect strip or member. It is not uncommon in precision drawer slide products to have an auxiliary member that rides on top of the drawer member. This auxiliary member is typically fastened in some permanent fashion to the drawer itself. As the name applies, the quick disconnect feature allows for easy engagement and disengagement of the drawer from the drawer slide assembly. The engagement/disengagement may be done by those working on the fabrication of the cabinet, or those who are installing the cabinet and from time to time, by the end user of the cabinet. The latching mechanism of some of the prior art includes a plastic lever, mountable on the quick disconnect strip, and which is biased in some fashion against a selected point on the drawer member so as to provide resistance against unintentional removal of the quick disconnect strip (and hence the drawer) from the drawer member.
In the prior art, the quick disconnect function is typically achieved through the usage of a longitudinal strip or member that runs approximately the same length as the drawer member itself. The detriment of providing such an auxiliary metal strip lies in the fact that it is yet more material commitment to the drawer slide design which serves only to provide an attachment means between the drawer slide itself and the side walls of the drawer. Therefore, it has been a long-standing problem in the art to reduce the additional metal content or to otherwise more simply achieve the quick disconnect function.
The quick disconnect strips of the prior art have also suffered from ergonomic limitations as well. Typically, the quick disconnect strips are oriented in the same way as the drawer member and the front end of the quick disconnect strip terminates near the front end of the drawer member. This results in the location of the actual quick disconnect xe2x80x9clatchxe2x80x9d in the vicinity of the front terminal point on the quick disconnect strip. Thus to cause the disengagement function to occur, the user is made to grip the front portion of the drawer and to simultaneously activate the latch to cause the quick disconnect strip to be disengaged, and then to elevate the drawer from the drawer member for removal. The problem with this approach is in the awkwardness of having to grip the drawer at the front end instead of more towards the middle portion of the drawer where the load would be more balanced. This is compounded by the fact that the user is also trying to activate the latch at the same time, as he/she is physically trying to manage the weight and positioning of the drawer, which makes the whole procedure more difficult than it needs to be.
Lastly, precision drawer slides of the telescoping variety are seldom equipped with what is known as progressive movement. The telescoping drawer slides can function in one of at least three different fashions, the first being a random advancement of the mechanism, whereby, upon the opening of the drawer the drawer member, and the intermediate member, move at entirely random rates relative to each other and to the cabinet member. Secondly, in some precision drawer slide designs, the drawer member and the intermediate member may be made to transition sequentially, such that the drawer member and the intermediate member move together in one fixed paring as the drawers open, and when the intermediate member reaches the end of it""s travel, the drawer member is then disengaged or unlatched, and allowed to continue to transition to an open position until it reaches the end of its travel. Thus, the term sequential. Lastly, progressive movement is defined by the proportional advancement of the drawer member and the intermediate member as the drawers open. The only prior art examples of this action use either strenuous componentry to achieve the result or as is the case in one example, the usage of a ball bearing to provoke the desired progression movement. In the case of the former, the progressive movement is caused by the disposition of a roller that is mounted to the intermediate member, which contacts a web portion of the drawer member and cabinet member simultaneously. Examples of this art are shown in Kovarik, et al, U.S. Pat. No. 5,344,228. With respect to the latter example, a ball bearing (or a pair of ball bearings) are similarly situated between the cabinet member and the drawer member and is held in position by a hole formed in the intermediate member. One key requirement in this prior art example though is the need to xe2x80x9cpre-loadxe2x80x9d the ball bearing in order to obtain the progression function. To do this, the diameter of the ball bearing is sized to be just slightly larger than the clearance allowed for the ball between the contact surfaces on the cabinet and drawer members when at rest. Thus there is imparted to the drawer slide in this particular approach, an added amount of sliding friction that has to be overcome which is contrary to the desired objectives of drawer slide design.
The prior art usage of rubber or elastomeric roller to accomplish the progressive action is also subject to several severe limitations. Invariably as the load on the drawer slide is expressed, there are some torsional and lateral effects on the channel members causing them to twist or to compress inwardly in response, which impacts components that are disposed in between the channel members. Likewise, there is a similar need to xe2x80x9cpre-loadxe2x80x9d the roller as was the case with the ball bearing. These effects can combine, individually or collectively to compress the roller beyond the initial desired level. When this happens, there is believed to occur a more severe distortion of the circumference of the roller, which further adds to the difficulties involved in obtaining a rolling engagement between the drawer and cabinet members. When this happens, the roller is more apt to slide along the course of its travel as the drawer slide is opened or closed.
It has been the observation of the applicant, that notwithstanding the desirability of sequential or progressive type of movements in precision drawer slide products; the offerings to date have not been able to fully satisfy the needs in the market. Sequential latching is noisy, and the mechanism may fail intermittently or permanently after a modest amount of cycling of the product. The progressive action suffers from the inability to perform well under increasing loads. Many times, the rollers or ball bearings used in the prior art have exhibited the tendency to slide or otherwise fail to progress the action between the drawer member and the intermediate member when confronted with applications in the upper ranges of the desired load levels of the drawer slide.
The present invention relates to a new drawer slide design that provides for a more robust cabinet member which competently handles static, lateral and torsional loads to such a degree that the members of the precision drawer slide can be reduced in metal thickness or cantilevered to a greater extent then was previously known to be practical. The precision drawer slide of the present invention comprises two members, one of which is a cabinet member that employs a unique hat section profile to achieve a surprising degree of rigidity and resistance to loadings. The drawer member of the present invention is inner-connectedly related to the cabinet member by means of ball bearings that are oriented through the usage of spaces or retainers, or through other conventional means. However, in the case of the present invention, the actual number of ball bearings necessary to achieve the desired performance level and their longitudinal spacing are greatly reduced over the prior art which allows one skilled in the art to take full advantage of the ability to cantilever the drawer member or reduce metal thickness of the present invention to a greater extent has been known.
Another embodiment of the present invention, a 3-member precision drawer slide is disclosed, comprising a cabinet member employing a unique hat section such as described above, an intermediate member which interconnectably related to said hat section, and a drawer member which is interconnectably related to said intermediate member. The three cooperating together to allow the transition of a drawer from a closed position to an open position, and vice versa by means of ball bearings that allows the telescoping action to occur in this fashion. Again, the ball bearings in this alternate embodiment, are disposed in longitudinal alignments, with one array as inner-ball bearings, and a second array as outer ball bearings, however, in such longitudinal spacing as to take full advantage of the load carrying capacity of the hat section cabinet member, so as to generate the cantilevered effect of the intermediate and drawer member combination.
In yet another embodiment of the present invention, a new quick disconnect feature is provided on a precision drawer slide product, which employs two quick disconnect components, a front quick disconnect trigger and rear quick disconnect engagement. Both components are mounted to a drawer individually, and are in alignment with their corresponding engagement slots found upon the drawer member. In this fashion, the quick disconnect concept of the present invention, allows for two component parts that totally replace the need for a longitudinal member that substantially equals the length of the drawer member. The quick disconnect feature of the present invention, therefore, reduces the material commitment and also by extension, the cost, while at the same time providing components that are compatible virtually with any length of drawer slide product associated with the present invention, without more.
An alternate quick disconnect feature is disclosed below as well. In this version, the quick disconnect strip is supplied with a trigger mechanism for latching the quick disconnect strip to the drawer member. The trigger is an unhanded component that has self-aligning elements and a provision for ensuring an affirmative return to the engagement position.
Yet another embodiment of the present invention is the inclusion of a roller bearing in-between a drawer member and cabinet member of a three membered precision drawer slide, wherein, said roller bearing is rotatably mounted onto the intermediate member in parallel alignment with the vertical webs of the three members. The roller bearing of the present invention providing progressive movement for the multi-membered precision drawer slide product, when transitioned from a closed position to an open position and vice versa. The progressive action thereby resulting from the active frictional engagement of the roller bearings as it contacts the inner web surfaces of the drawer member and the outer web surface of the hat section of the cabinet member. Furthermore, the roller bearing progressive movement of the present invention has increasing frictional engagement and durability as the lateral loads increase on members of the precision drawer slide product itself.
It is therefore, an object of the present invention to provide for a new precision drawer slide that reduces the material commitment for its manufacturer, as a result of the ability to reduce the length of the individual members forming the telescoping slide.
It is also an object of the present invention to provide for a new quick disconnect feature for a precision drawer slide that eliminates the necessity for the longitudinal metal strip that substantially equals the drawer slide member in length.
It is also an object of the present invention to provide a quick disconnect feature with a trigger release that is mountable to a sidewall of a drawer by means of a screw fastener.
In an alternate version of a quick disconnect feature, a trigger mechanism is provided with self-aligning elements and an affirmative return to engagement position means.
It is also an object of the present invention to provide for a precision drawer slide product that minimizes the number of ball bearings that have to be dedicated to provide the transitional functioning of the product.
It is also an object of the present invention to provide a novel hat section profile, that is mountable onto a cabinet, and which increases the robustness and load carrying capacity of the precision drawer slide.
It is also an object of the present invention to provide a cabinet member with an exposed flange area for increased ease of mounting or installation by the cabinet manufacturer.
It is also an object of the present invention to provide a precision drawer slide product with a roller bearing for progressive movement through the interaction between an outer member and an inner-member being mounted on an intermediate member.
It is also an object of the present invention to provide a precision drawer slide product with a roller bearing for resisting longitudinal twisting and preventing metal-to-metal contact between the slide members.
These and other objects of the present invention will be more fully appreciated and understood, as they are set forth below.